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The Truth About Low-Carb DietsBy Jamie Hale Almost everyone knows someone who has used a low carb diet. They have used it themselves had a friend use it or are getting ready to use it . Are these diets magic? Are they safe? Can I really eat all of the cheese and meat I want ? Will I die if I go into ketosis? These are just a few common questions I hear in regards to questions that concern low carb diets. In this series of articles I will present readers with scientific facts and my practical observations for implications concerning low carb diets. Some low carb supporters will not like what I will have to say. Some low carb haters will not like what I have to say. The objective of these articles are to educate readers on the practical implications of low carb dieting. Some will be offended and some will say how can that be. Either way sit back and enjoy as I attempt to shed light on the highly talked about topic - low carb diets (ketogenic diets) I have provided a brief overview of some the topics that will be discussed in this article. What type of changes occur while using low carb diets Do low carb diets make me mean Do low carb diets spare muscle Can I gain weight on a low carb diet How much weight can I expect to lose Can this diet help my medical condition Different types of low carb diets Why you need to cycle higher days of carbs Who needs low carb diets Are they safe for children Are they beneficial for athletes Before we move any further let me introduce the word ketogenic. Must of you reading this article are probably familiar with the world as it implies low carb or restriction of carb intake. Simply put for our purposes the words ketogenic and low carb are synonymous. A couple of other comments I would like to make before we move on. This comment is for Low Carb supporters that swear of all vegetables and fruits. Get on medline.com and do some research. Go to the library and look through some journals. A complete diet for long term use needs to incorporate greens and some fruits to be healthy. A short term diet devoid of fruits and vegetables might not be that bad, but rejecting greens and any fruits for life is a bad idea. This comment is for the low carb haters. One of the number one reasons most of America is fat is because of chronically high insulin levels. Which is primarily contributed to excessive carb intake. Don't get me wrong I am not blaming high carbohydrate intake on all of our obesity problems. I should probably say excessive and the wrong types of carbohydrate at the wrong times are the problem. At the same time the answer is not to eat all of the saturated fat we can find : which can contribute to insulin insensitivity, elevated TG's, increased lipogenesis and digestive problems. What is a ketogenic diet? A diet that causes ketone bodies to be produced by the liver, and shifts the body's metabolism away from glucose in favor of fat burning. A ketogenic diet restricts carbohydrates below a certain level (generally 100 per day). The ultimate determinant of whether a diet is ketogenic or not is the presence or absence of carbohydrate. Protein and fat intake vary. Contrary to poplar belief eating fat is not what causes ketosis. In the past starvation diets were used often to induce ketosis. I will repeat myself again and say lack of carbohydrate or presence of ultimately determines if the diet is ketogenic. In most eating plans the body runs on a mixture of protein, fats and carbohydrates. When carbohydrates are severely restricted and glycogen storage (glucose in muscle and liver) is depleted the body begins to utilize other means to provide energy. FFA (free fatty acids) can be used to provide energy, but the brain and nervous system are unable to use FFA's. Although the brain can use ketone bodies for energy. Ketone bodies are by products of incomplete FFA breakdown in the liver. Once they begin to accumulate fast and reach a certain level they are released , accumulated in the bloodstream and cause a state called ketosis. As this occurs there is a decrease in glucose production and utilization. There is also less reliance on protein to meet energy requirements by the body. Ketogenic diets are often referred to as protein sparing as they help to spare LBM whiled dropping body fat. In regards to ketogenic diets there are two primary hormones- insulin, glucagon that need to be considered. Insulin can be described as a storage hormone as it's job is to take nutrients out of the bloodstream and carry them to target tissues. Insulin carries glucose from the blood to the liver and muscles, and it carries FFA from the blood into adipose tissue (stored fat triglyceride). On the other hand glucagon breaks down glycogen stores (especially in the liver) and releases them into the blood. When carbs are restricted or removed insulin levels drop while glucagon levels rise. This causes enhanced FFA release from fat cells, and increased FFA burning in the liver. This accelerated burning of FFA in the liver is what leads to ketosis. There are a number of other hormones involved with this process as well. In general we refer to three different types of ketogenic diets. 1) STANDARD KETOGENIC DIET- A diet containing l00 or less grams of carbohydrates is referred to as STANDARD KETOGENIC DIET 2)TARGETED KETOGENIC DIET- consuming carbohydrates around exercise, to sustain performance without affecting ketosis. 3)CYCLICAL KETOGENIC DIET- alternates periods of ketogenic dieting with periods of high carbohydrate intake The Beginning of Ketogenic diets Originally ketogenic diets were used to treat obesity and epilepsy. In general ketogenic diets are similar to starvation diets in the responses that occur in the body. More specifically these two states can be referred to as starvation ketosis and dietary ketosis. These similarities have led to the development of modern day ketogenic diets. Ketogenic dieting has been used for years in the treatment of childhood epilepsy. In the early 1900's times of total fasting was used to treat seizures. This caused numerous health problems and could not be sustained indefinitely. Due to the impracticalities and health problems occurring with starvation ketogenic diets researchers began to look for a way to mimic starvation ketosis while consuming food. They determined that a diet consisting of high fat, low carb and minimal protein could sustain growth and maintain ketosis for a long period of time. This led to the birth of the original ketogenic diet in 1921 by Dr. Wilder. Dr Wilder's diet controlled pediatric epilepsy in many cases where drugs and other treatments failed. New epilepsy drugs were invented during the 30's, 40's and 50's and ketogenic diets fell to the wayside. These new drugs lead to almost disappearance of ketogenic diets during this time. A few modified ketogenic diets were tried during this time such as the MCT (medium chain triglycerides) diets, but they were not welly accepted. In 1994 the ketogenic diet as a treatment for epilepsy was re-discovered. This came about in the story of Charlie a 2yr old with seizures that could not be controlled with mediacions or other treatment including brain surgery. Charlie's father had found reference to the diet through his research and ended up at John Hopkins medical center. Charlie's seizures were completely controlled as long as he was on the diet. The huge success of the diet prompted Charlie's father to start the Charlie foundation. The foundation has produced several videos, and published the book The Epilepsy Diet Treatment: An Introduction to the Ketogenic diet. The foundation has sponsored conferences to train physicians and dietians to implement the diet. The exact mechanisms of how the ketogenic diet works to control epilepsy are still unknown, the diet continues to gain acceptance as an alternative to drug therapy. Obesity Ketogenic diets have been used for at least a century for weight loss. Complete starvation was studied often including the research of Hill, who fasted a subject for 60 days to examine the effects. The effects of starvation were very successful in regards to treatment of the morbidly obese as rapid weight loss occurred. Other characteristics attributed to ketosis, such as appetite suppression and sense of well being, made fasting even more attractive for weight loss. Extremely obese patients have been fasted for up to one year and given nothing but vitamins and minerals. The major problem with complete starvation diets is the loss of body protein, primarily from muscle tissue. Protein losses decrease as starvation contines, but up to one half of the total weight loss can be contributed to muscle and water loss. In the early 1970's Protein Sparing Modified Fasts were introduced. These diets allowed the benefits of ketosis to continue while preventing losses of bodily proteins. They are still used today under medical supervision. In the early 70's Dr. Atkins introduced Dr. Atkins Diet Revolution With millions of copies Sold the diet generated a great deal of interest. Dr. Atkins suggested a diet limited in carbohydrate but unlimited in protein and fat. He promoted the diet as it would allow rapid weight loss, no hunger and unlimited amounts of protein and fat. He offered just enough research to allow the diet recognition. Although most of the evidence supporting the diet was questionable. During the 1980's Michael Zumpano and Dan Duchaine introduced two of the earliest CKD's THE REBOUND DIET for muscle gain and then the modified version called THE ULTIMATE DIET for fat loss. Neither diet became very popular. This was likely due to the difficulty of the diet and the taboo of eating high fat. In the early 90's Dr. Dipasquale introduced the ANABOLIC DIET . This diet promoted 5 days of high- fat-high protein-low carb consumption whle eating high carbs and virtually anything you wanted for two days. The diet was proposed to induce a metabolic shift within the five days of eating low carbs (30 or less). The metabolic shift occurred as your body switched from being a sugar buring machine to a fat-burning machine. A few years later Dan Duchaine released the book UNDERGROUND BODYOPUS: MILITIANT WEIGHT LOSS AND RECOMPOSITION . The book included his CKD diet which he called BODYOPUS. The diet was more specified than the Anabolic Diet and gave exercise recommendations as well as the basics concerning exercise physiology. Most bodybuilders found the diet very hard to follow. The carb load phase required eating every 2 hrs and certain foods were prescribed. I personally loved the book, but felt the difficulty of the diet made it less popular. In this author's opinion Ducahine's book is a must read for anyone interested in Nutrition. Ketogenic Diets have been used for years to treat specific conditions such as obesity and childhodd epilepsy. The effects of these diets have proven beneficial in a number of these well documented cases, but for some reason when we mention any type of low carb diet (ketogenic diet) people begin to tell us about how their doctor or friend told them it would kill them or how that diet was shown to damage the liver or kidneys. Keep in mind epileptic children have been in ketosis for up to three years and shown no negative effects; quiet the opposite. The weight loss in morbidly obese patients has been tremendous and the health benefits numerous. Maybe before coming to the conclusion that all types of ketogenic diets are bad other factors need to be considered such as activity levels, type of ketogenic diet, length of ketogenic diet, past eating experience, purpose of ketogeninc diet, individual body type and response to various eating plans, current physical condition, and quality of food while following ketogenic diet. As you can see there are numerous factors that come into play when saying a diet is good or bad. I think people should take the time look at the research and speak with various authorities in regards to low carb diets before drawing conclusions from the they says. Relevant research in regards to ketogenic dieting Efficacy and safety of the ketogenic diet for intractable childhood epilepsy: Korea multicentric experience Chul Kang H, Joo Kim Y, Wook Kim D, Dong Kim H, Dept of pediatrics, Epilepsy center, Inje Univ Coll of Med, Sanggye Paik Hospital, Seoul Korea The purpose of the study was to evaluate the safety of the ketogenic diet, and to evaluate the prognosis of the patients after successful discontinuation of the diet in infants, children and adolescents with refractory epilepsy. The study looked at patients who had been treated with KD during 1995 through 2003 at Korean multicenters. The outcomes of the 199 patients enrolled in the study at 6 and 12 months were as follows: 68% and 46% of patients remained on the diet, 58% and 41% showed a reduction in seizures, including 33% and 25% who became seizure free. The complications were mild during the study, but 5 patients died during the KD. No significant variables were related to the efficacy, but those with symptomatic and partial epilepsies showed more frequent relapse after completion of the diet. The researchers concluded the KD is a safe and effective alternative therapy for intractable epilepsy in Korea, although the customary diet contains substantially less fat than traditional Western diets, but life-threatening complications should be monitored closely during follow up. The body derives it's energy from four key fuels 1) glucose 2)proteins 3) free fatty acids 4) ketones. The primary determinant of the fuel utilized is the availability of carbohydrate. The body has three storage units that can be utilized during times of calorie deprivation: 1) carbohydrate, which is sotred in liver and the muscles 2) protein, which can be converted to glucose in the liver 3) fat, which is stored primarily in adipose tissue. Under specific conditions a fourth fuel comes into play -ketones which are derived from the incomplete breakdown of free fatty acids. Under normal dietary conditions ketones play a minimal role in energy prodcition. During times of Low carb dieting or starvation diets ketones impact energy production significantly. When looking at storage of bodily fuels triglyceride is the most abundant. Carrbohydrate stiores are minimal compared to protein and fat. Although stored protein could possibly fuel the body longer than stored carbohydrates too much reliance and protein for energy could result in death. The average person has enough body fat to live for months without food. There are numerous documented cases where morbidly obese patients were fasted for up to one year. In gereral the body utilizes the fuel that is most abundant in the bloodstream. As an example when glucose elevates in the bloodstream the body will utilize mostly glucose. When glucose levels begin to lower the body uses less glucose. When decreasing carbohydrate availability the body begins a metabolic shift resulting in a higher dpendence on fat for energy. Many trainees like to point to the fact that a high carb diet is protein sparing. Keep in mind while a high carb diet is protein sparing it is also fat sparing. High levels of carbohydrates decrease the use of fat for fuel. In the initial days of fasting prtein is converted to glucose. This is where some people formed the idea that low carb diets were muscle wasting. WITH AN ADEQUATE AMOUNT OF PROTEIN INTAKE THESE MUSCLE WASTING EFFECTS CAN BE MINIMIZED IN THE EARLY STAGES OF THE DIET. AS THE BODY BECOMES KETOGENIC PROTEIN IS SPARED. Most tissues of the body can use FFA for fuel. Although, there are tissues that cannot utilize FFA for fuel including brain, red blood cells, renal medulla, bone marrow and type 2 muscle fibers. One of the biggest mis-conceptions about human physiology is the belief that the brain can only run on glucose. Under normal dietary conditions the brain primarily functions by using glucose, but under conditions of ketosis the brain can run efficiently by using ketone bodies. Arguably the most important tissue in terms of ketone body usage is the brain which can derive up to 75% of it's energy requirements from ketone bodies once adaptation occurs. Other research indicates that ketone bodies are the preferred fuel of many tissues. One exception is the liver which does not use ketones for fuel, but relies on FFA. There are several factors which influence the fuel used by the body. Factors influence fuel utilization 1) amount of each nutrient being consumed 2) level of hormones such as insulin and glucagon 3) bodily stores of each nutrient 4) levels of regulatory enzymes for glucose and fat breakdown Amount of nutreint being consumed There are four substances that we dervie calories from these include 1) carbohydrate 2)protein 3)fats 4)alcohol. Generally speaking, the body utilizes glucose in direct proportion to the amount of carbohydrate being consumed. If carb intkae increases the bodies utilizaton increases and vice-versa. When protein intake increases protein oxidation will also increase to a degree. If protein intake drops the body will use less protein for fuel. The body attempts to maintain body protein at constatn levels. The amount of dietary fat being consumed does not significantly increase the amount of fat used for fuel by the body. Fat burning is determined indirectly by alcohol and carbohydrate consumption. The consumption of alcohol will almost completely inhibit the bodies ability to burn fat for fuel. The greatest rates of fat oxidaton will occur when carbohydrates and alcohol are limited. Levels of muscle glycogen also regulate how much fat is used by the muscle. Hormones Insulin's primary role is to keep blood glucose in a range of 80-120 mg/dl. When blood glucose raises above 120 the pancreas releases insulin to lower blood glucose. The greatest increase of blood glucose come after the consumption of carbohydrate (different types have differing effects). Protein causes a smaller increase in insulin output because some individual amino acids can be converted to glucose. FFAs and ketones can also stimulate an inslun respone, but the response is a great deal less than that which comes from the consumption of protein or carbs. As blood glucose drops insulin levels decrease as well. With the decrease in insulin the body begins to break down stored fuels. Fat cells are broken down into glycerol and FFAs and released into the bloodstream. Proteins are broken down into individual amino acids and glycogen stored in the liver is broken down into glucose and released into the bloodstream. Glucagon is a hormone released from the pancreas that acts to control blood glucose as well. Glucagon acts to raise blood glucose when it drops below normal. Glucagon's main action is in the liver as it breaks down liver glycogen and releases it into the blood stream. Glucagon also plays an important role in ketone body formation in the liver. Glucagon released is stimulated by exercise, decreasing blood glucose and insulin and protein consumption. Elevated levels of insulin inhibut the pancreas from releasing glucagon From the information provided above it is apparent that insulin and glucagon play antagonist roles to one another. Insulin is primarly a storage hormone: while glucagons's primary role is to moblilze fuel stores for use by the body. Growth hormone is another hormone which has numerous effects on the body. GH is released in respone to exercise, a decrease in blood glucose, and carb restriction or fasting. GH is a growth promoting hormone increasing protein synthesis in the muscle and liver. GH also acts as a FFA mobilizer. Most of the anabolic effects of GH are mediated through a class of hormones called insulin-like growth factors (IGFs). IGF-1 is the key contributor to anabolic growth in most of the bodies tissues. GH stimulates the liver to produce IGF-1 but only in the presence of insulin. High GH levels in combination with high insulin levels (protein carb meal) will raise IGF-1 levels increasing anabolic reactions in the body. On the other end high GH levels with low insulin levels will not cause and increase in IGF-1 levels. The thyroid gland produces two hormones, thyroxine (T4), and triidothyronine (T3). In the human body T4 is primarily a storage form of T3 and plays few physiological roles itself. Thyroid hormones can have an effect on all tissues of the body. Chronically low carb intake can signifcatinly lower thyroid hormone. Cortisol is a catabolic hormone released by the adrenal glands. Cortisol is involved in gluconeogenesis as well as fat breakdown. Cortisol is required for life but excessive amounts can be detrimental to health causing protein breakdwon, bone tissue degradation, immune system impairment, connective tissue and skin weakening. Adrenaline and noradrenaline (epinephrine and norepinephrine) are released from the adrenal glands and are frequently referred to as fight or flight hormones. These hormones are generally released in response to cold, exercise, or fasting. Epinephrine is released from the adrenal medulla, while nor epinephrine is released primarily from the nerve terminals. The primary role the adreanl hormones adrenaline and nor - adrenaline play in the ketogenic diet is to stimulate free fatty acid release from fat cells. In humans, insulin and adrenaline and nor-adrenaline have the most profound effect on fat mobilization. In general, insulin acts as storage hormone while adrenaline and nor-adrenaline stimulate fat breakdown. LIVER GLYCOGEN All foods coming through the digestive tract are processed initially in the liver. In general, liver glycogen is the key determinant of the body's tendency to store or breakdown nutrients. There is a direct correlation between liver glycogen levels aond bodyfat levels. High levels of liver glycogne are usually related to higher bodyfat levels. The liver serves as a storehouse for glycogen. Liver glycogen is broken down in response to glucagon and released into the bloodstream. When liver glycogen is full the body is generally in an anabolic state. Incoming nutrients are stored as glycogen, proteins, and triglycerides. This is sometimes called the fed state. When liver glycogne is depleted the liver shifts roles and becomes catabolic. Glycogen is broken down into glucose, protein is broken down into amino acids, and triglycerides are broken down inot FFA's. This is often referred to as the fasted state. Ketogenesis will occur when liver glycogen is depleted, blood glucose drops, and the insulin/glucagon ratio shifts. ENZYME LEVELS Enzyme levels are primarily determined by the nutrients being ingested in the diet and the hormonal levels that result from the ingestion. When carb intake is high and glucose and glycogen storage is stimulated the enzymes involved in fat breakdown are inhibited. On the other hand when insulin drops the enzymes involved with glucose use are inhibited and the enzymes involved in fat breakdwon will increase. Relevant research in regards to ketogenic dieting A comparative study of two diets in the treatement of primary exogenous obesity in children Pena L, Pena M, Gonzalez J, Claro A, One hundred and four children, ages six to fourteen with exogenous obesity were subjected to two different diets, Ketogenic (low carb) and hypocaloric, for eight weeks.Body weight, serum triglycereides, cholesterol, glucose tolerance test, blood glucose, and plasma insulin determination were measured before and after diets. The results revealed significant differences in bodywt, and triglyceride concentration, with both diets. There were significant differences in the fasting insulin levels, insulinogenic index, and insulin concentration after a glucose tolerance test in the patients treated with a KD diet. Reference McDonald, L (1998) The Ketogenic Diet. Lyle McDonald. |
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